SQL adapter: unexpected message type 'Z' in IDLE state

[aljazerzen]

When querying EdgeDB's SQL adapter with this query:

edgedb=# select 'bad uuid'::uuid;

... the conection is closed from the server side and server reports these logs:

INFO 1198263 - 2024-06-19T19:28:22.179 edb.server: Serving admin on /home/aljaz/.local/share/edgedb/_localdev/.s.EDGE
DB.admin.5656


INFO 1198263 _localdev 2024-06-19T19:28:27.361 edb.server: introspecting database 'main'
================================================================================
SQL Input
================================================================================
SELECT/*<pg.SelectStmt at 0x7f9e2f1483e0>*/
        ('bad uuid')::uuid

================================================================================
SQL Output
================================================================================
SELECT/*<pg.SelectStmt at 0x7f9e25fdc560>*/
        ('bad uuid')::uuid AS "col~1"

WARNING 1198263 _localdev 2024-06-19T19:28:29.033 edb.server: Released an unhealthy pgcon; discard now.
--------------------------- Exception occurred: unexpected message type 'Z' in IDLE state ---------------------------

1. RuntimeError: unexpected message type 'Z' in IDLE state

----------------------------------------------------- Traceback -----------------------------------------------------

    uvloop/handles/stream.pyx, line 837, in uvloop.loop.__uv_stream_on_read_impl

    uvloop/loop.pyx, line 109, in uvloop.loop.run_in_context1
        > none = NoneConstantType()
    edb/server/pgcon/pgcon.pyx, line 3197, in edb.server.pgcon.pgcon.PGConnection.data_received
        > self.fallthrough_idle()
    edb/server/pgcon/pgcon.pyx, line 2849, in edb.server.pgcon.pgcon.PGConnection.fallthrough_idle
        > raise RuntimeError(

RuntimeError: unexpected message type 'Z' in IDLE state
ERROR 1198263 - 2024-06-19T19:28:29.034 asyncio: Fatal error on transport UnixTransport
protocol: <edb.server.pgcon.pgcon.PGConnection object at 0x7f6851fe95d0>
transport: <UnixTransport closed=False reading=False 0x7f6859503e00>
ERROR 1198302 - 2024-06-19T19:28:29.037 postgres: invalid input syntax for type uuid: "bad uuid" at character 54
INFO 1198302 - 2024-06-19T19:28:29.037 postgres: SELECT/*<pg.SelectStmt at 0x7f9e25fdc560>*/
INFO 1198302 - 2024-06-19T19:28:29.038 postgres:                ('bad uuid')::uuid AS "col~1"
INFO 1198263 _localdev 2024-06-19T19:28:29.038 edb.server: Connection discarded to backend database: main
INFO 1198263 _localdev 2024-06-19T19:28:30.051 edb.server: Backend connections to database main: 1 were established i
n at least the last 1.0 seconds.

Found when working on #7462

[aljazerzen]

start transaction; select 'bad uuid'::uuid; rollback;